The Domain Name System (DNS) is the part of the Internet infrastructure that translates human-readable domain names into the Internet Protocol (IP) numbers needed to establish TCP/IP communication over the Internet. That is, DNS allows users to refer to web sites, and other resources, using easier to remember domain names, such as “www.example.com”, rather than the numeric IP addresses, such as “123.4.56.78”, assigned to computers on the Internet. Each domain name is made up of a series of character strings (labels) separated by dots. The right-most label in a domain name is known as the “top-level domain” (TLD). Examples of well-known TLDs are “.com”: “.net”; “.org.” etc.
The responsibility for operating each TLD (including maintaining a registry of the second-level domains within the TLD) is delegated to a particular organization, known as a domain name registry (“registry”). The registry is primarily responsible for converting domain names to IP addresses (“resolving”) through DNS servers that maintain such information in large databases, and operating its top-level domain. Significantly, the original DNS was specified in the era of ASCII, and thus relied on Latin alphabet and numerical characters for domain names. However, as an increasing portion of the Internet users worldwide are speakers of languages that do not use the Latin alphabet, the introduction of Internationalized Domain Names (IDNs) was initiated as a way for these users to navigate the Internet in their own language. IDNs are domain names, or Web addresses, represented by local language characters. The local language domain name may be followed by .com or .net (for example, .com). IDNs utilize non-ASCII characters and are for use in markets where English is not the primary language. They give users a convenient mechanism for accessing Web sites in more than 350 languages.
Because the DNS does not inherently support characters from non-English scripts, international-language names to be registered must be converted into an encoded sequence of supported characters. A standardized methodology has been adopted including the Internet Architecture Board (IAB) principle of a single DNS root and standards developed by the IDN Working Group of the Internet Engineering Task Force (IETF), which uses pre-pending codes to the domain name to apply appropriate code translation rules to the ASCII Compatible Encoding (“ACE”). A brief summary of an IDN methodology is described below.                Consider the domain name .com, for example.        The internationalized portion, , becomes “3b7vcv67.”        
To complete the registration for the IDN, a two character extension, known as a prepend, and two hyphens (“−”) are added by the registrar to flag the domain name as an IDN. The prepend is “xn.”. Thus the registration in this example is sent to the registry as “xn—3b7vev67.com.” This representation is referred to as the domain name's ACE (ASCII Compatible Encoding) representation.
As detailed above, the IDNs in the Shared Registration System rely on standardized translations of foreign characters to ACE format. However, in foreign languages such as traditional and simplified Chinese, there may be different forms of a character. In light of this complexity, words or characters can take different forms before and after translation. That is words that should be treated identically for purposes of registration and resolution may have different variants and Unicode representations. This can lead to problems in domain name registration and resolution, including the potential of allowing different users to register what should be considered the same domain name by using different forms of the characters.
One solution to the multiple character problem is to block all language-equivalent IDN names for a single registration. This approach allows a single form of the Chinese IDN, but blocks all other forms from later registration. This solution has been recognized by the IDN Working Group of the IETF, which has defined an “IDL Package” as part of the JET Guidelines for IDN. However, because a single Chinese character can have many variants, domain names including several Chinese characters together can result in an overwhelming number of possible variants for a single domain name. Without a special approach the storage required to effectively block IDN names of significant length in Chinese language variants Can be prohibitive. Similar ways of dealing with this problem include other types of reserving or registering all potential variants of an IDN, which can present significant burdens as well. Known methods are also limited in their ability to interpret IDNs that may include different types of character variations within a name. For example, a user may attempt to register or resolve an IDN by inputting a mixture of traditional and simplified Chinese characters that a registration or resolution system may NI to adequately decipher when listed together.